In a known design of such a contactor, the contactor comprises a cylindrical annular armature in which a contactor coil is arranged. The coil actuates a movable core, which is thereby displaced axially so as to act on a control rod, which extends in its center through a fixed core in the form of a disc, which is arranged at a front axial end of the armature. The control rod, in its turn displaces a movable contact into and out of engagement with two fixed contact terminals. These contact terminals are arranged to be connected in the power supply circuit of the starter motor, and are carried in the base portion of a cover hood of the contactor. The cover hood has the general form of a cylindrical pot, so that it includes a lateral skirt portion which defines within it a housing in which the movable contact is contained.
It is also known to equip the contactor with an electronic control circuit for controlling operation of the contactor. Such a circuit typically includes a printed circuit board, with the components of the circuit being carried on the circuit board. It is also known to arrange the electronic control circuit within a hermetically sealed casing, which is then secured on the outside of the starter, on the support pedestal or bracket of the starter, or on the contactor itself, or again on the casing of the electric starter motor. The casing for the electronic control circuit may also be fixed on the bodywork of the vehicle, in the engine compartment.
It is then necessary to provide wires or cables which connect the casing of the control circuit, firstly with the starter contactor, and secondly with the other appropriate components of the vehicle which play a part in the control of the engine starting operation, for example the ignition switch, the anti-theft system, an electronic computer unit for controlling fuel injection, ignition, and so on.
The arrangement of the electronic control circuit in an independent casing, therefore, leads to the need to provide an additional component, that is to say a separate control unit casing, which is relatively bulky and which further makes it necessary to provide additional electrical connections, and to carry out particular assembly operations on the vehicle.